OK, Ive had a 4 stroke for one day. Yesterday, it started and ran great. I ran two tanks through it for break-in, and started it 3-4 times after. Today, it "popped back" and spun the prop nut off two times. The third time, the spinner backing plate exploded when I tried to start it.. OK........ What the heck is going on?? The high speed was 3 out, per brake-in instructions. Any idea's?

Scoot

Possibly over primed, or possibly too lean. Are you using an electric starter or are you starting by hand?

I used the starter motor to turn it over w/o the glow on to prime. Hooked-up the glow and BAM, prop spins off. I tried once with out spinning to prime, same result.

OK, I removed glow, spun the motor over with starter. Put glow plug back in and didnt prime it. I started right up.

Guess it was overprimed/flooded. Glad you got it going.

I had to fine tune the throttle/servo/idle stop settings, and it started at an idle perfectly 6 or 7 times. Sounds like a lawn mower! LOL

Thanks for the help guys. Scoot

I don't prime my engines with the starter. I turn the prop with my finger, choking with another over the intake or exhaust until the fuel reaches the carb. Then I turn it over without choking 5-6 times. I hook up the igniter and hit it with the starter until it fires. Works every time.-BW